Portable electric router



14, 1958 N. D. POTTER PORTABLE ELECTRIC ROUTER Filed April 9', 1957 IOb mm W R.

m w mm N M T A N 4110M M k ATTORNEYS PURTABLE ELECTRIC ROUTER Nathaniel D. Potter, Baltimore, Md., assignor to The Black & Decker Manufacturing Company, Towson, Md., a corporation of Maryland Application April 9, 1957, Serial No. 651,679

6 Claims. (Cl. 144-134) The present invention is concerned generally with structural improvements in portable electric tools relating to adjustability of one part with respect to the other; more particularly to a rack and pinion type adjusting mechanism and its relation to the overall structure in a portable electric hand router. However certain features of the invention may find application in other environments.

The present invention is hereinafter described as embodied in a portable electric hand router to which it is particularly adapted and in which environment it has decided advantages over prior structures. Generally speaking, portable hand routers of the type here considered have a supporting base structure slidably engageable with the work including a generally cylindrical upright sleeve receiving the lower end of an electric motor casing, the electric motor being vertically or axially adjustable with respect to the sleeve to vary the position relative to the base of a tool bit chucked at the lower end of the motor shaft coaxially aligned with the sleeve.

Various cooperating structures have been provided by the prior art between the motor casing and the base for attaining the required adjustment. Thus in some cases a cylindrical split sleeve type base with clamping bolt means engaged in integral lugs on opposite sides of the split has been the simple expedient used to permit axial sliding adjustment and clamping of a motor unit with a corresponding outer cylindrical casing surface received in the sleeve. Other routers have added to such structure a longitudinal rack on the motor casing engaged by pinion rotatably journalled on the sleeve formation of the base. At times such rack and pinion mechanisms have included on or in association with the pinion shaft a graduated sleeve which may be set relative to a fixed index mark either to zero or a selected reading, whereby the linear or axial shift effected or desired may be directly observed. Such structures for indication of the axial adjustment however have had certain untoward features of relative complexity of structure in view of the end to be attained, certain awkwardness in manipulation, or stepwise rather than continuous variability of the setting of the graduated scale. Also prior router structures under some circumstances have been awkward in the overall manipulation for effecting the required adjustment.

By the present invention there is provided in a router conventional in its overall structure a rack and pinion adjustment of novel character which serves also as a means for clamping or holding the adjusted elements of motor and base in selected position and further provides in the router a motor casing structure having what may be termed a squared end whereby the router may be inverted upon the squared end as a stable supporting base for more convenient and precise setting of the tool position. The latter feature is obtained by forming the top of the motor casing, that is the end opposite the toolbearing shaft end, with at least three well spaced extreme end points defining a plane perpendicular to the axis of the router to provide a stable base. By such Fatented ct. 14, 1958 Further the strain on the rack and pinion mechanism is accordingly smaller, with less wear on the same to prolong its useful life.

However, it is to be noted that although such feature of the motor casing is particularly advantageous with rack and pinion adjusting structures, it also may be advantageously incorporated in other types of routers, such as those including a male threaded motor casing axially adjustable by its threaded engagement with a female threaded base sleeve, or those including the simple telescoped cylindrical motor casing and split clamping sleeve structure; since even with the latter structures the great convenience resulting from invertability of the router as a whole upon motor end as a stable base is clearly meritorious per se and as permitting more precise measurement of the bit position relative to the base in setting operations.

An object of the present invention is then to provide a portable tool including as a relatively large part thereof a motor assembly which may be inverted or stood up right in stable position upon one end of the motor casing for convenience in adjustment of a tool carried at the opposite end of the motor unit. Another object is the provision, in a portable hand tool such as an electric router having a motor unit axially shiftable with respect to a base assembly or other portion of the portable tool, of a base formation at one end of the motor casing which permits convenient adjustment of the base assembly of the tool.

A still further object is the provision of a rack and pinion type adjustment in a tool of the character described wherein clamping of the mechanism in selected position is achieved in the rack and pinion assembly itself. A still further object is the provision of a rack and pinion type adjusting assembly which includes a position shift indicating graduated sleeve coupled by simple means to the pinion operating shaft in such manner that an infinitely continuous setting of the sleeve may be obtained.

Other objects and advantages will appear from the following description and the drawing, wherein:

Fig. 1 is a front elevational view of a portable electric router embodying the present invention;

Fig. 2 is a top plan view of the router of Fig. l with the electric cord and switch omitted for clarity;

Fig. 3 is a fragmentary sectional view taken longitudi nally through the rack and pinion tool adjustment mechanism of the router; and

Fig. 4 is a detail view of the pinion shaft of the adjustment mechanism.

For convenience in description and structural recitation of the claims, relative positions of elements will be set forth in terms of a router disposed as in the drawing. As indicated by general reference characters in Fig; l, the router includes a high speed commutating electric motor M, telescoped in a base assembly B to permit adjustment of the motor-and hence of a router bit or other rotationally driven tool T carried in the chuck C mounted on the bottom end of the motor shaft-in an axial sense relative to the base assembly, by an adjusting and clamping mechanism A of the rack-and-pinion type.

The motor M includes the upper and lower housing members 10, ll fitted together endwise and secured by ventilating air inletapertures 13, the field corestructure 14 is bolted endwise for telescoped disposition within the cylindrical shell comprising the lower housing member 11. 'lihe lower end of 'the lattenis spanned by" alower shaft bearing supporting integral spider '15, spaced from the field core to provide space for .a motor ventilation fan 16:0n: the armature shaft'exhausting through spider. openings=17 to: direct air-as a chip cle'aning blast downwardly upon the working area.

In the base assembly B, the generally: cylindrical sleeve 20 has an integral bottom flange 21 to which is secured a suitably apertured sub-base disk22of plastic, compressed fiber plastic orother 'materialqsuitable for sliding contact with thework; and further has a pair of diametrically disposed handles 23, as usual in such tools. The interior cylindric surfaceof the base sleeve 20 and the exterior of lower'motor'housing- 1 1 are sized for a sliding fit to the region where-the top of sleeve 20 encountersshoulder ll'a: on the upper end of the housing 11. Diametrically opposed openings in the sleeveallow accesswith wrenches to the chuck for therelative positionshown, as well as escape-of working debris removed by the ventilating exhaust air blast.

The structure as thus far described is generally-similar ina broad sense to known routers. However particular features arenow described, relating to the adjustment'and maintenance of a selected bit position relative to the base by axial shifting of the motor assembly.

Midway between the handles, one side of thesleeve 20 has an interr-upted vertical external rib formation 25a, 25b permittingthe underlying internal surface of the sleeve to be internally slottedat 26a, 26bfor-accommodation of a vertical rack element 27 secured to the lower motorhousing 1 1 by screws 28, 29. The side walls of the slot by embracing the sidesof' the rackmay'providea guide preventing turning of the base with respecttothe motor and thereby aiding retentionof the rack andpinion elements in proper operative relation.

integrally formed on the sleeve on opposite sides of the centerline of the aforementioned rib are a pair ofgenerally similar outwardly projecting lugs 31, 32'with aligned bores to receive the-pinion-shaft 33 as hereinafter described with its integral pinion formation 34meshing with rack 27.

To the left (as represented in the drawings) of the knurled head 36, the pinion shaft includes successively a short cylindrical portion .37 providing a shoulder 37a bearing against a corresponding end face of-the right lug 32 and having near its middle a fiat-bottomed circumferential groove 37b; a-portion- 38journalled in the cor-' responding bore of lug 32; the pinion formation 34; a portion 39still further reduced in diameter and journalled through bushing 40 in a corresponding bore of left lug 31; and a threaded end41, with clamping wing nut 42; The wing nut bears on the left side of lug 31 in clamping the router at selected adjustment.

A graduated sleeve 43, rotatably mounted on shaftpor tion 37 between the shaft manipulating head or knob 36 and lug 31, is however frictionally coupled with the shaft by-an O-ring'44 located in groove 37b. Thus, with the pinion-shaft stationary; the sleeve may be grasped at its knurled right end 43a, to set the series of circumferentially'spaced graduations, at its left end as desired to, a conveniently located index mark 46 on the adjacent lug 32. Preferably the scale divisions of the graduated sleeve are integral divisions reading in units of linear shiftof the motor casing relative to the base corresponding to rotation of the pinionshaft.

A still further point of structure relating to easy, exact adjustment and clampingofthe router for a desired tool position resides in the top end'structure of motor casing member 10, which has an undulating, upwardly extending rim formation resulting in four equispaced crests a. Each crest is shown located, in angular sense midway between the successive external'longitudinal rib enlargement 10b provided in the motor-casing structure to accommodate bores for screws 12. As the crests 1011 are the extreme endward points of the casing terminating in a plane perpendicular to the axis of the router, and further are well spaced by location at the extreme outward radial extent of the member 10, a stable supporting base is provided for the router when upended for adjustments.

When the router is upended on such stable base, not only are the graduated sleeve, clamping nut and pinion shaft the more. easily manipulated for precise final adjustment of the tool, byvirtue of the convenientsteady position of the router; but also because the mass of the relatively light base is lifted rather than the'much greater mass of the motor assembly the'ease and precision of adjustment is furthered. For the latter reason also wear and tear on the rack and pinion mechanism is minimized.

The sleeve scale may be set exactly to zero by overcoming the O-ring frictional engagement without movingthe pinion shaft; the wing nut '42 then loosened'and the-desired shift in toolposition-made by turning, the pinion shaft to bri'ngthe corresponding scale graduation to'the index 46. Obviously at the users option, the sleeve scalemay be set to a reading corresponding in location to a-desired shift, and thepinion shaft turned until the zero markcdincides with the index. Then thewingnut 42 is tightened to hold the pinion shaft stationary by the axially directed forces developed between'the nut,

- shaft shoulder 37a and the respective abutting lug faces.

In furtherance of this clamping function, a pair 'of parallel circumferentiallydirected slots 47, 48 cut through the-wall of sleeve at opposite sidesof' the lugs 31, 32,

allow the 'pinionshaft to serve as a clamping bolt whereby the underlying sleeve area may be deflected to apply clamping force-on the motor casing;

I claim: "1'. Ina portable electric router or thelike having as a work engaging base-a'bottom-flanged generally cylindrical sleeve,'amotor assembly having a cylindrical lower housing portion coaxially slidably telescoped in the base sleeve, and means for clamping the motorassembly and work engaging-basein selected relative axial positions, that improvement comprising: a top motor housing end portion adapted to form a stable base for the router when upended thereon; a rack extending longitudinally on said motor housing portion; a pinion shaft carrying apinion inengagement with the rack; integral lug means'formed on the exterior of the'base sleeve journalling' said pinion shaft; saidpinion-shaft having opposite end'portions projecting through said lugmeans, one projecting end being enlarged to provide a manipulating'knob spacedfrom the lug'means and an intervening cylindrical portion of reduced diameter providing a shaft shoulder bearing against an adjacent side'of said lug means, the other projecting end of the shaft being threaded and provided with a clamping nut bearing on an opposite side of the lug means;'said cylindrical portion having a circumferential groove'between the knob and'shoulder; a sleeve rotatably mounted on said cylindrical portion and having a series ofcircumferentially spaced graduations located for convenient reference with respect to an index mark on the base; and a friction coupling between the second said sleeve and shaftcomprising an O-ring locatedin said groove.

2. In aportable electric router or the like havingas a work engaging base a bottom-flanged generally cylindricahslecve, a motor'assembly with a cylindrical lower housing-portion axially a'djustably received in the base sleeve, and means'for clamping the motor assembly and work engaging-base in selectedrelative axial positions, that ir'nprovement'comprisingza top motor housing end portion including at least three extreme angularly spaced endwise projections terminating in a common plane perpendicular'to'the motor axis and each projection radially spaced from the motor axis in a location adjacent the circumferential margin of the said end portion, whereby the same is adapted to form a stable base for the router when upended thereon.

3. In a portable electric hand tool including a motor assembly having at one axial end a driven working element, that improvement comprising: a motor housing end portion at the other axial end of the assembly, said end portion including at least three extreme angularly spaced endwise projections terminating in a common plane perpendicular to the motor axis and each projection radially spaced from the motor axis in a location adjacent the circumferential margin of the said end portion, whereby the same is adapted to form a stable base for the tool when upended.

4. In a portable electric router or the like having as a work engaging base a bottom-flanged generally cylindrical sleeve, a motor assembly having a cylindrical lower housing portion coaxially slidably telescoped in the base sleeve, and means for clamping the motor assembly and work engaging base in selected relative axial positions, that improvement comprising: a rack extending longitudinally on said motor housing portion; a pinion shaft carrying a pinion in engagement with the rack; integral lug means formed on the exterior of the base sleeve journalling said pinion shaft; said pinion shaft having opposite end portions projecting through said lug means, one projecting end being enlarged to provide a manipulating knob spaced from the lug means and an intervening cylindrical portion of reduced diameter providing a shaft shoulder bearing against an adjacent side of said lug means, the other projecting end of the shaft being threaded and provided with a clamping nut bearing on an opposite side of the lug means; said cylindrical portion having a circumferential groove between the knob and shoulder; a sleeve rotatably mounted on said cylindrical portion and having a series of circumferentially spaced graduations located for convenient reference with respect to an index mark on the base, and a friction coupling between the second said sleeve and shaft comprising an O-ring located in said groove.

5. In a portable electric router or the like having as a work engaging base a bottom-flanged generally cylindrical sleeve, a motor assembly having a cylindrical lower housing portion coaxially slidably telescoped in the base sleeve, and means for clamping the motor assembly and work engaging base in selected relative axial positions, that improvement comprising: a rack extending longitudinally on said motor housing portion; a pinion shaft carrying a pinion in engagement with the rack; a pair of opposed integral lugs formed on the exterior of vided with a clamping nut bearing on an opposite side of the other lug; said cylindrical portion having a circumferential groove between the knob and shoulder; a sleeve rotatably mounted on said cylindrical portion and having a series of circumferentially spaced graduations located for convenient reference with respect to an index mark on the base, and a friction coupling between the second said sleeve and shaft comprising an O-ring located in said groove.

6. In a portable electric router or the like having as a work engaging base a bottom-flanged generally cylindrical sleeve, a motor assembly having a cylindrical lower housing portion coaxially slidably telescoped in the base sleeve, and means for clamping the motor assembly and work engaging base in selected relative axial positions, that improvement comprising: a rack extending longitudinally on said motor housing portion; a pinion shaft carrying a pinion in engagement with the rack; and a pair of opposed integral lugs formed on the exterior of the base sleeve at opposite sides of said rack and journalling said pinion shaft at locations spaced axially from opposite sides of the pinion; said lugs being separated from each other and separated fro mthe axially adjacent areas of the sleeve; said pinion shaft having opposite end portions projecting through said lugs, one projecting end being enlarged to provide a manipulating knob spaced from the adjacent lug and an intervening shaft shoulder bearing against a side of said adjacent lug, the other projecting end of the shaft being threaded and provided with a clamping nut bearing on an opposite side of the other lug.

References Cited in the file of this patent UNITED STATES PATENTS 1,532,683 Carter Apr. 7, 1925 1,565,790 Carter Dec. 15, 1925 1,745,780 Casey Feb. 4, 1930 1,899,883 Sacrey Feb. 28, 1933 2,613,704 Sacrey Oct. 14, 1952 2,714,408 Pedersen Aug. 2, 1955 

